New York: Scientists have found that three-dimensional paper-based microbial fuel cells can create power in an environmentally-friendly way without the use of any outside power. "All power created in this device is usable because no electricity is needed to run the fluids through the device. This is crucial in the advancement of these devices and the expansion of their applications," said senior author Nastaran Hashemi from the Iowa State University in Ames. The team demonstrated a proof-of-concept, published in the journal TECHNOLOGY, that 3D paper-based microbial fuel cell (MFC) could take advantage of capillary action to guide the liquids through the MFC system and eliminate the need for external power. In the study, the paper-based MFC ran for five days and showed the production of current as a result of biofilm formation on anode. The system produced 1.3 µW (microwatt) of power and 52.25 µA (microampere) of current yielding a power density of approximately 25 W/m3. The biofilm formation on the carbon cloth during the test provided further evidence that the current measured was the result of the bio-chemical reaction taking place. This was important because the biofilm play a vital role in current production of a microbial fuel cell. According to the researchers, increased biofilm size and thickness ultimately leads to increased current production. The device for the first time demonstrated the longer duration of use and ability to operate individually, a development that could help increase the number of situations where microbial fuel cells can be applied. The researchers are now exploring options to better control the voltage output and create constant current.